The present application relates to a light detection apparatus and a light detection method that detect light emitted from a specimen using a photo-diode.
In the field of medical treatment, scientific research, and the like, detection of light emitted from a specimen is often performed. For example, by irradiating a specimen with excitation light to measure fluorescence or phosphorescence generated in the specimen, it is possible to detect that the specimen contains material that generates such light.
For the detection of light, a photo-diode is generally used. The photo-diode is capable of outputting an amount of light as a current. However, in the case where highly accurate measurement is necessary, noise is problematic. Increasing a light reception time period (exposure time period) of the photo-diode can make a signal-to-noise ratio (SNR) larger, but there is a problem that a measurement time period increases. This is remarkable especially in the case where weak light is measured by long-time exposure, for example, in fluorescence measurement.
In view of this, Japanese Patent Application Laid-open No. 2009-128648 (hereinafter, referred to as Patent Document 1) describes a microscope observation system. The microscope observation system is capable of measuring a noise level of an image sensor in a light-shielding state before measurement to adjust an exposure time period based on the noise level. With the microscope observation system, it is possible to reduce the influence on the measurement result by setting the exposure time period so that noise is within a certain range.